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The translocation of species outside their natural range is a threat to aquatic biodiversity globally, especially freshwater fishes, as most are not only susceptible to predation and competition but readily hybridize with congeners.Running River rainbowfish (RRR, Melanotaenia sp.) is a narrow‐ranged, small‐bodied freshwater fish that recently became threatened and was subsequently listed as Critically Endangered, owing to introgressive hybridization and competition following the translocation of a congeneric species, the eastern rainbowfish (Melanotaenia splendida).To conserve RRR, wild fish were taken into captivity, genetically confirmed as pure representatives, and successfully bred. As the threat of introgression with translocated eastern rainbowfish could not be mitigated, a plan was devised to translocate captive raised RRR into unoccupied habitats within their native catchment, upstream of natural barriers. The translocation plan involved careful site selection and habitat assessment, predator training (exposure to predators prior to release), soft release (with a gradual transition from captivity to nature), and post‐release monitoring, and this approach was ultimately successful.Two populations of RRR were established in two previously unoccupied streams above waterfalls with a combined stream length of 18 km. Post‐release monitoring was affected by floods and low sample sizes, but suggested that predation and time of release are important factors to consider in similar conservation recovery programmes for small‐bodied, short‐lived fishes. [ABSTRACT FROM AUTHOR]

Aim: Fires can severely impact aquatic fauna, especially when attributes of soil, topography, fire severity and post‐fire rainfall interact to cause substantial sedimentation. Such events can cause immediate mortality and longer‐term changes in food resources and habitat structure. Approaches for estimating fire impacts on terrestrial species (e.g. intersecting fire extent with species distributions) are inappropriate for aquatic species as sedimentation can carry well downstream of the fire extent, and occur long after fire. Here, we develop an approach for estimating the spatial extent of fire impacts for aquatic systems, across multiple catchments. Location: Southern Australian bioregions affected by the fires in 2019–2020 that burned >10 million ha of temperate and subtropical forests. Methods: We integrated an existing soil erosion model with fire severity mapping and rainfall data to estimate the spatial extent of post‐fire sedimentation threat in waterways and in basins and the potential exposure of aquatic species to this threat. We validated the model against field observations of sedimentation events after the 2019–20 fires. Results: While fires overlapped with ~27,643 km of waterways, post‐fire sedimentation events potentially occurred across ~40,449 km. In total, 55% (n = 85) of 154 basins in the study region may have experienced substantial post‐fire sedimentation. Ten species—including six Critically Endangered—were threatened by post‐fire sedimentation events across 100% of their range. The model increased the estimates for potential impact, compared to considering fire extent alone, for >80% of aquatic species. Some species had distributions that did not overlap with the fire extent, but that were entirely exposed to post‐fire sedimentation threat. Conclusions: Compared with estimating the overlap of fire extent with species' ranges, our model improves estimates of fire‐related threats to aquatic fauna by capturing the complexities of fire impacts on hydrological systems. The model provides a method for quickly estimating post‐fire sedimentation threat after future fires in any fire‐prone region, thus potentially improving conservation assessments and informing emergency management interventions. [ABSTRACT FROM AUTHOR]

The redclaw crayfish (Cherax quadricarinatus) is a freshwater decapod crustacean, cultured in numerous countries worldwide for both food and ornamental purposes. Redclaw crayfish has become an important aquaculture species due to its physical and biological traits, relatively easy breeding, and a short growing‐out period to reach commercial size. Bacterial infections are the second‐most studied pathogens of freshwater crayfish. However, redclaw crayfish rickettsiosis, caused by Coxiella cheraxi, was reported in only a few scientific papers in the early 2000s, in Australia and Ecuador. Coxiella cheraxi is a rod‐shaped intracellular bacterium that can cause mortality of 22%−80% in naturally infected crayfish. In experimental infections, mortality rates may be even higher (40%−90%). Coxiella cheraxi is closely related to Coxiella burnetii, the agent of Q‐fever, which affects ruminants (goats, sheep, and cattle) and occasionally may cause zoonotic infections. According to the scientific knowledge available, C. cheraxi is a species‐specific pathogen because it has been only detected in Cherax quadricarinatus and thus far, there is no evidence of a zoonotic potential. In this study, we describe an outbreak of rickettsiosis in a batch of redclaw crayfish imported to Israel from an Australian hatchery, observed 2 months after introduction in a quarantine facility. Initial mortality was evaluated through histopathology, revealing infection by rickettsia‐like organisms (RLO) that were subsequently investigated by molecular analysis and transmission electron microscopy examination. Phylogenetic analysis revealed that the detected RLO were closely related to C. cheraxi from a single source (Australian strain TO98), available in free publicly accessible databases. After 5 months in quarantine, almost 99% of the crayfish population had died. Our findings raise valuable questions related to aquatic animal trade and the importance of mitigation measures, such as quarantine and routine diagnostic procedures, to limit the spread of infectious diseases. [ABSTRACT FROM AUTHOR]

How populations of aquatic fauna persist in extreme desert environments is an enigma. Individuals often breed and disperse during favorable conditions. Theory predicts that adaptive capacity should be low in small populations, such as in desert fishes. We integrated satellite‐derived surface water data and population genomic diversity from 20,294 single‐nucleotide polymorphisms across 344 individuals to understand metapopulation persistence of the desert rainbowfish (Melanotaenia splendida tatei) in central Australia. Desert rainbowfish showed very small effective population sizes, especially at peripheral populations, and low connectivity between river catchments. Yet, there was no evidence of population‐level inbreeding and a signal of possible adaptive divergence associated with aridity was detected. Candidate genes for local adaptation included functions related to environmental cues and stressful conditions. Eco‐evolutionary modeling showed that positive selection in refugial subpopulations combined with connectivity during flood periods can enable retention of adaptive diversity. Our study suggests that adaptive variation can be maintained in small populations and integrate with neutral metapopulation processes to allow persistence in the desert. [ABSTRACT FROM AUTHOR]

Coarse particulate organic matter (CPOM) is a fundamental resource in freshwater streams, providing food, shelter and habitat for diverse invertebrate taxa and playing a key role in metabolism in low‐order streams. Benthic CPOM stocks are determined by rates of supply and breakdown of detritus and by channel retentiveness (i.e. the capacity for the channel to trap and retain CPOM). We focussed on factors affecting the retentiveness of channels, which theoretically differs among streams with different sediment sizes and concomitant channel morphology.We developed a new, rapid method to measure retentiveness using line‐intercept surveys along transects. With this rapid approach, we surveyed 32 sites from three types of streams (smooth sandy channels, n = 10; gravel channels of intermediate roughness, n = 12; rough cobble channels, n = 10) in Victoria, south‐eastern Australia, and tested the simple hypotheses that: (1) retentiveness increases in channels with increasing channel roughness (i.e. sandy versus gravel versus cobble‐bed streams); (2) different types of channel features (e.g. log jams, cobbles, depositional areas) differ in the efficiency with which they retain CPOM. The line‐intercept survey method was readily adapted to measure retentiveness as m of retentive structure per m of transect (i.e. the Linear Coverage Index) and trapping efficiency as m of CPOM per m of retentive element, for 10 different types of retentive elements.Unexpectedly, the retentiveness of channels did not increase with channel roughness. This occurred because channels with different roughness were dominated by different types of retentive structure. Retentive structure in cobble sites was dominated by cobbles themselves, which were highly retentive in other studies but poorly retentive in our system. Gravel and sand sites had more log jams and depositional areas, such as pools and backwaters, and these features were more effective at trapping CPOM. Thus, retention of CPOM was highest in gravel and sand sites.Our method provides a new tool for investigators testing hypotheses about CPOM retention in streams. The method is rapid, requires a minimum of equipment and personnel, and may be applied in any wadeable stream. Retentiveness is calculated in intuitive units that are directly comparable among sites and may have utility as variables in models of CPOM dynamics. We hope this method will open up new avenues for research that may shed light on how CPOM stocks vary among streams, with implications for diversity of aquatic fauna and ecosystem functions such as decomposition. [ABSTRACT FROM AUTHOR]

The welfare of aquatic animals is receiving increasing attention around the world, and this should be reflected in the veterinary curricular. Veterinary students in Australia and New Zealand ranked the importance of five pre-selected topics on aquatic animal welfare and ethical issues for newly qualified veterinarians in an online survey. They ranked aquatic animals' health and welfare issues, husbandry techniques of farmed fish, and the use of antibiotics as being of high importance for their first day in practice, with pain and distress associated with angling and trawling practices (fishing) and euthanasia ranking moderate to high. Females assigned more importance to fishing, health and welfare issues, and husbandry techniques of farmed fish than did males. Students in the early stages of study assigned more importance to fishing than did senior students. To the authors' knowledge, this is the first study to investigate what importance veterinary students place on their competence regarding aquatic animal welfare and ethics. Gaining an understanding of how veterinary students prioritize these issues, and if this differs based on gender and stage of study, will help veterinary educators to better prepare graduates to address concerns surrounding the welfare of aquatic animals. This could be achieved by careful consideration of course content and where in the curriculum this material is taught, as well as reiterating key messages in the senior years and addressing changing student attitudes as they progress through the course. [ABSTRACT FROM AUTHOR]

The ornamental fish trade in Australia has an estimated value of AUD$350 million and involves importation of up to 20 million fish from 26 approved countries each year. Critical reviews indicated that the biosecurity system did not fully manage the risks associated with fish that were sub-clinically infected with diseases such as megalocytiviruses, or the threats posed by emerging diseases. Subsequent reforms have placed a greater emphasis on managing biosecurity risks off-shore at the source, coupled with an on-arrival surveillance system to assess compliance with biosecurity regulation. This presentation at the first global Conference in Aquatic Animal Epidemiology in Oslo, Norway in September 2016, describes the Department of Agriculture Water Resources' current initiatives to address increased risks in real-time while facilitating safe trade. The department is developing an innovative real-time, responsive risk-based surveillance capability to detect systemic failures on the part of the animal health authorities. The program involves a risk-based sampling algorithm on ornamental fish imported into Australia and testing for megalocytiviruses, spring viraemia of carp virus and Aeromonas salmonicida. We present the system and the results from several trials. The information generated by the verification surveillance system will be quantitative and semi-quantitative in nature and will form the basis of the department's response to detect systematic non-compliances by overseas authorities. Evidence collected through the ongoing analysis of surveillance data will become the basis of real-time feedback to overseas authorities for remedial action at source. Delays in resolving non-compliance issues could result in the suspension of off-shore equivalent measures from particular sources. [ABSTRACT FROM AUTHOR]

Abstract A multi-disciplinary pelagic ecosystem study of the Great Australian Bight (GAB) examined the micronekton communities and bioregionalisation in this area that harbours significant predator populations. Micronekton community structure and biomass differed between the eastern and central regions of the GAB. Regional differences were mainly driven by relatively high abundance of krill (Nematoscelis megalops, Nyctiphanes australis and Euphausia similis) in east GAB and high abundance of Maurolicus australis and chaetognaths in central GAB. Central GAB was also characterised by relatively high abundance of gelatinous zooplankton and small-bodied cephalopods. Lanternfishes were used as a model pelagic group to investigate the bioregional setting of the GAB. The analyses indicated that the oceanic habitats of the GAB had bioregional affinities with the subtropical Indian Ocean. However, over the continental slope, the east GAB had bioregional affinities with the Subtropical Convergence and grouped with western and southern Tasmania and the southern Tasman Sea. Lanternfish assemblage groups were compared against existing regionalisations that are based on physicochemical variables and the Delphi Method. No single existing scheme suitably reflected lanternfish assemblage distributions, but parsimonious boundaries from existing schema were identified. This study demonstrates that the central GAB, where oil-and-gas exploration occurs alongside Marine Protected Area management, needs to be considered as a separate bioregion to the east GAB for the purposes of identifying conservation values and monitoring requirements. [ABSTRACT FROM AUTHOR]

Fire plays an important role in many ecosystems, but megafires are increasing the area burnt in forested regions globally. The 2019–2020 megafires in south-eastern Australia were unprecedented with respect to area burnt and the spatial extent of high-severity fire. Yet, there is limited knowledge regarding the impact of these megafires on biodiversity, especially aquatic fauna. Here we investigate the impact of the 2019–2020 megafires on the distribution of a semi-aquatic monotreme thought to be in decline: the platypus, Ornithorhynchus anatinus. We leveraged extensive pre-fire environmental DNA (eDNA) sampling and coupled this with additional sampling at two timepoints post-fire, to conduct a Before-After-Control-Impact (BACI) study. We used site occupancy-detection modelling to estimate platypus occupancy across fire affected and non-fire affected sites over time as well as the interaction between occupancy, high rainfall, and fire severity. We detected a negative effect of fire presence on platypus occupancy in both post-fire time periods. Platypus occupancy was also predicted to be lower at sites that experienced high rainfall post-fire and were situated within watersheds that had a large proportion burnt at high-severity. With area burnt and the extent of high-severity fire increasing globally, and predictions of more extreme rainfall events in south-eastern Australia in the future, the impact of fire on aquatic fauna requires greater consideration in post-fire assessments and biodiversity management more generally. The use of eDNA sampling and detection methods in a BACI framework provides a promising means to fill these knowledge gaps but does require pre-emptive sampling. [ABSTRACT FROM AUTHOR]

Australian waters are home to a number of vocal species of fish. Cataloguing the acoustic characteristics and temporal patterns of choruses and their locations can provide significant information for long-term monitoring of vocal fishes and their ecosystems. In coastal waters off Port Hedland, Western Australia, two seafloor positioned sea-noise loggers, located 21.5 km apart in 8 and 18 m of water, recorded for an 18-month period. Numerous sound sources were detected, including mooring and vessel noise, humpback whale song and a large variety of fish signal types. Seven fish choruses were identified, occurring predominantly between late spring and early autumn (wet season) and displaying energy from 50 Hz to >4 kHz. Many of these choruses exhibited acoustic characteristics similar to choruses previously reported elsewhere, for some of which the source species or families have been identified. Distinct diurnal patterns in the choruses were observed, associated with sunrise or sunset and in some cases, both. While choruses were predominantly recorded on different days, there were at total of 80 days when more than one chorus was present at the same site. Some pairs of choruses present on the same day exhibited various combinations of temporal and frequency partitioning, while others displayed predominant overlap in both spaces. [ABSTRACT FROM AUTHOR]

Growth is a fundamental biological process, driven by a multitude of intrinsic (within-individual) and extrinsic (environmental) factors, that underpins individual fitness and population demographics. Focusing on the comprehensive information stored in aquatic and terrestrial organism hard parts, we develop a series of increasingly complex hierarchical models to explore spatial and temporal sources of growth variation, ranging in resolution from within individuals to across a species. We apply this modeling framework to an extensive data set of otolith increment measurements from tiger flathead (Platycephalus richardsoni ), a demersal commercially exploited fish that inhabits the warming waters of southeast Australia. We recreated growth histories (biochronology) up to four decades in length from seven fishing areas spanning this species' range. The dominant pattern in annual growth was an age-dependent, allometric decline that varied among individuals, sexes, fishing areas, years, and cohorts. We found evidence for among-area differences in growth-rate selectivity, whereby younger fish at capture were generally faster growers. Temporal growth variation was partitioned into two main sources: extrinsic year to year annual fluctuations in environmental conditions and persistent cohort-specific growth differences, reflecting density dependence and/or juvenile experience. Despite low levels of among-individual growth synchrony within areas, we detected a regionally coherent signal of increasing average growth rate through time, a trend related to oceanic warming. At the southerly (poleward) range limit, growth was only weakly related to temperature, but farther north in warmer waters this relationship strengthened until closer to the species' equatorward range limit, growth declined with increasing temperatures. We partitioned these species-wide and area-specific phenotypic responses into within- and among-individual components using a reaction norm approach. Individual tiger flathead likely possess sufficient growth plasticity to successfully adapt to warming waters across much of their range, but increased future warming in the north will continue to depress growth, affecting individual fitness and even population persistence. Our modeling framework is directly applicable to other long-term, individual-based, data sets such as those derived from tree rings, corals, and tag-recapture studies, and provides an unprecedented level of resolution into the drivers of growth variation and the ecological and evolutionary implications of environmental and climatic change. [ABSTRACT FROM AUTHOR]

A variety of techniques have been used to monitor platypus populations to assess the impacts of the threats they face, but each technique has limitations. In this study we investigated the novel use of in-stream microchip readers, to remotely monitor the movements of microchipped wild platypuses. Over 13 months, we recorded movements of 18 microchipped individuals past nine fixed locations in the Inglis Catchment in northwest Tasmania, using three units of which all were capable of detecting Trovan® unique microchips and two were additionally capable of detecting ISO microchips. Each site was monitored one or two times, for durations of 8-39 days. We undertook direction of movement investigations during two monitoring periods, by placing the antennas from two systems in the same creek within 3 m of each other. In a total of 264 days of monitoring, 528 platypus observations were made from 18 individual platypuses, consisting of 13 of 18 (72%) platypuses captured at the monitoring sites within 16 months prior to monitoring, two platypuses captured at other sites in the same time period, and three of seven (43%) individuals microchipped 3-5 years previously. This number of platypus observations, in combination with the stable number of platypuses observed per day, the range of movement behaviours recorded and the results of the direction of movement investigations, indicates that at appropriate sites, in-stream microchip readers are an effective method of monitoring the movements and survivorship of microchipped wild platypuses. [ABSTRACT FROM AUTHOR]

Autonomous acoustic telemetry monitoring systems have been deployed in aquatic ecosystems around the globe - from under ice sheets in the Arctic to coral reefs in Australia - to track animals. With tens of thousands of tagged aquatic animals from a range of tax a, vast amounts of data have been generated. As data accumulate, it is useful to reflect on how this information has advanced our understanding of aquatic animals and improved management and conservation. Here we identify knowledge gaps and discuss opportunities to advance aquatic animal science and management using acoustic telemetry monitoring. Current technological and analytical shortfalls still need to be addressed to fully realize the potential of acoustic monitoring. Future interdisciplinary research that relies on transmitter-borne sensors and emphasizes hypothesis testing will amplify the benefits of this technology. [ABSTRACT FROM AUTHOR]

Understanding environmental and climatic drivers of natural mortality of marine mammals is critical for managing populations effectively and for predicting responses to climate change. Here we use a 17-year dataset to demonstrate a clear relationship between environmental forcing and natural mortality of inshore marine mammals across a subtropical-tropical coastline spanning a latitudinal gradient of 13° (>2000 km of coastline). Peak mortality of inshore dolphins and dugongs followed sustained periods of elevated freshwater discharge (9 months) and low air temperature (3 months). At a regional scale, these results translated into a strong relationship between annual mortality and an index of El Niño-Southern Oscillation. The number of cyclones crossing the coastline had a comparatively weak effect on inshore marine mammal mortality, and only in the tropics. Natural mortality of offshore/migratory cetaceans was not predicted by freshwater discharge, but was related to lagged air temperature. These results represent the first quantitative link between environmental forcing and marine mammal mortality in the tropics, and form the basis of a predictive tool for managers to prepare responses to periods of elevated marine mammal mortality. [ABSTRACT FROM AUTHOR]

1. Effective management of aquatic fauna requires knowledge of the ways in which populations in different catchments and sub-catchments are connected. A powerful way to estimate this is using genetic markers, which provide information on the average amount of genetic connectivity among populations over generations. Although many studies of genetic connectivity have appeared in the literature, there are innumerable species that have not been studied. 2. This study explores whether it is possible to make broad generalisations about population connectivity, based on readily available information in the form of species life history and architecture of the aquatic habitat. 3. A number of models have been proposed to explain the pattern of connectivity shown by aquatic species with different life-history characteristics, for example, the stream hierarchy model, Isolation by Distance, the Death Valley Model, the headwater model and panmixia. 4. In this study, we propose a dichotomous key to assign species to different models of potential connectivity. The key is based on a few very simple questions about the life history of the species and the geographical arrangement of study sites. We then assessed the performance of the key with 109 data sets of Australian fish and macroinvertebrates, using genetic data to provide an estimate of realised connectivity. 5. The realised connectivity fitted the proposed potential connectivity model in over 70% of cases, and we suggest this might be a useful initial approach for managers where empirical data are lacking. [ABSTRACT FROM AUTHOR]

Abstract: Agricultural pesticides are widely used and can affect freshwater organisms. We applied a spatially explicit exposure model, validated for central Europe, to estimate exposure to insecticides through runoff for streams in south-eastern Australia. The model allows the identification of streams potentially affected by insecticide runoff located in 10×10km grid cells. The computation of runoff relies on key environmental factors such as land use, soil texture, slope and precipitation. Additionally, the model predicted the ecological effect of insecticides on the macroinvertebrate community. We predicted insecticide surface runoff that results in a moderate to poor ecological quality for streams in half of the grid cells containing agricultural land. These results are in good accordance with the results obtained by estimating pesticide stress with a biotic index (SPEARpesticides) based on macroinvertebrate monitoring data. We conclude that the exposure and effect model can act as an effective and cost-saving tool to identify high risk areas of insecticide exposure and to support stream management. [Copyright &y& Elsevier]

1. The unique aquatic fauna of the island-like groundwater springs of arid inland Australia raises important questions as to how aquatic species persist in very isolated and fragmented habitats and the role that dispersal may play in mitigating/mediating the influence of landscape structure and determining population structure. By determining the relationship between genetics and geography (i.e. phylogeography), the historical processes responsible for population structure can be determined. 2. We undertook comparative phylogeographic studies of invertebrates from springs south of Lake Eyre. Clusters of springs lying within and between surface drainage catchments (which provide a potential connection between springs) were sampled, and the phylogeographic structure of four coexisting species, an ostracod Ngarwa dirga, a snail Fonscochlea accepta, an isopod Phreatomerus latipes and an amphipod Wangiannachiltonia guzikae, was examined. 3. Clear differences in the geographic patterns of genetic structure were found amongst the four species. No discernable genetic structure was found in ostracod and snail populations, even amongst springs lying 20 km apart in separate surface catchments; isopod populations were highly genetically structured amongst springs located in separate catchments, but not within catchments, whilst amphipod populations were highly genetically structured amongst springs both within and between catchments. 4. The results suggest that differences in dispersal ability of each species, and not the overall fragmented nature of the springs, may have led to large differences in phylogeographic history. Interestingly, the relative dispersal ability of these species may be related to their vulnerability to and recovery from large-scale flood events. Therefore, despite the highly isolated and fragmented nature of the springs, the landscape has not strongly influenced the population structure of the aquatic invertebrate community as a whole nor has it led to the evolution of common life histories. [ABSTRACT FROM AUTHOR]

The article explores the use of seagrass microhabitats by olive-headed sea snakes Disteria major to avoid tiger sharks Galeocerdo cuvier predation in Shark Bay, Australia. It notes that prey frequently avert their predators and favor predator-abundant areas to assist escape or discourage attack. It mentions that snakes utilized microhabitats which is equal to food supply when sharks were in short supply and avoided edges. Moreover, it states that it seems that D. major quantify danger across seagrass banks using variability in predator density and seek low-encounter microhabitats.

Strata of Jurassic age occur extensively across onshore Australia, but they are predominantly of non-marine origin. Marine Jurassic strata have only limited onshore exposure in northwestern and central-western Australia, with thick marine sequences lying offshore on the North West Shelf. The richest petroleum province in Australia is located at the shelf's southern end, where the Dingo Claystone represents an important source rock for oil and gas. By and large, non-marine deposits, including economic coals, are distributed in the eastern states. Jurassic stage boundaries, in the main, are poorly constrained with respect to the Australian sedimentary succession. New work on microfossils, plants, fish, and zircon dating is providing a basis for improved correlation across Australian basins, with overseas successions, and recent international IUGS geologic timescales. [ABSTRACT FROM AUTHOR]

1. Floodplain rivers in Australia’s wet/dry tropics are regarded as being among the most ecologically intact and bio-diverse lotic ecosystems in the world, yet there have been relatively few community-based studies of their aquatic fauna. 2. To investigate relationships between hydrological connectivity and biodiversity in the region, macroinvertebrates were collected from sites within two contrasting floodplain rivers, the ‘tropical’ Gregory River and ‘dryland’ Flinders River systems, during the dry season and analysed at various spatial scales. A subset of sites was re-sampled in the following dry season to explore temporal variation. The fauna consisted of 124 morphotaxa, dominated by gatherers and the Insecta. 3. As predicted, hydrological connectivity (the lotic or lentic status of waterbodies) had a major influence on macroinvertebrate assemblage composition and diversity, both in space and time. Assemblages from waterbodies with similar connection histories were most alike, and beta-diversity between assemblages was greatest between lotic and lentic waterbodies, tending to increase with increasing spatial separation. 4. At smaller spatial scales, a number of within-waterbody, habitat and water quality characteristics were important for explaining variation (61%) in the taxonomic organization of assemblages, and characteristics associated with primary productivity and habitat diversity were important for explaining variation (45%) in the functional organization of assemblages. However, much of the small-scale environmental variation across the study region appeared to be related to broad-scale variation in hydrological connectivity, which had both direct and indirect effects on macroinvertebrate assemblages. 5. Conservation of the biodiversity in Australia’s wet/dry tropics may depend on conserving the natural variation in hydrological connectivity and the unregulated flow of floodplain rivers. [ABSTRACT FROM AUTHOR]

Abstract: Numbers of species at mid-shore levels on rocky shores were sampled across 415 km to test hypotheses about patterns along the coast of New South Wales, Australia. In two different years, sampling in winter revealed increased numbers of species sampled over shores with increasing distance from north to south. There was no such trend during summer. The latitudinal increase in species was due to sessile fauna and to a lesser extent, to mobile fauna. Encrusting and foliose algae did not contribute to the pattern. The seasonal difference was mostly due to changing numbers of species between seasons. The numbers of species per sample-unit (i.e. species-density) always increased with distance from north to south in both seasons and both years when grain-size of sampling was quadrats (scattered <1 m apart) or sites on the shore (20 – 30 m apart). Species-density was unreliable as an estimate of diversity along the coast, because it revealed spurious trends in summer when there was no increased number of species from north to south. Analyses of densities, dispersions, frequencies of occurrences and multivariate dissimilarities of the organisms did not explain why species'' densities showed a trend along the coast. Comparisons of diversity where species are not censused, but must be sampled, are made difficult by the dispersions of individual taxa across sample-units. [Copyright &y& Elsevier]

Laboratory studies show that predatory cane toads ( Bufo marinus) exhibit specialized toe-luring behavior that attracts smaller conspecifics, but field surveys of toad diet rarely record cannibalism. Our data resolve this paradox, showing that cannibalism is common under specific ecological conditions. In the wet–dry tropics of Australia, desiccation risk constrains recently metamorphosed toads to the edges of the natal pond. Juvenile toads large enough to consume their smaller conspecifics switch to a primarily cannibalistic diet (67% of prey biomass in stomachs of larger toads). Cannibalistic attack was triggered by prey movement, and (perhaps as an adaptive response to this threat) small (edible-sized) toads were virtually immobile at night (when cannibals were active). Smaller metamorphs were consumed more frequently than were larger conspecifics. The switch from insectivory to cannibalism reflects the high dry season densities of small conspecifics (in turn, due to desiccation-imposed constraints to dispersal) and the scarcity of alternative (insect) prey during dry weather. Our study pond (102 m in circumference) supported >400 juvenile toads, which consumed many metamorphs over the course of our study. Toads appear to be low-quality food items for other toads; in laboratory trials, juvenile toads that fed only on conspecifics grew less rapidly than those that ate an equivalent mass of insects. This effect was not due to parotoid gland toxins per se. Thus, cane toads switch to intensive cannibalism only when seasonal precipitation regimes increase encounter rates between large and small toads, while simultaneously reducing the availability of alternative prey. [ABSTRACT FROM AUTHOR]

The historical exploitation of marine resources in Queensland has only been partially documented. In particular, the history of the commercial fishing of dugongs and marine turtles has received comparatively little scholarly attention. Since European settlement in Queensland, various human activities have exploited these resources. We present documentary and oral history evidence of the scale of those industries. Based on extensive archival and oral history research, we argue that diverse fishing practices occurred and that the sustained exploitation of dugongs, green turtles, and hawksbill turtles led to observable declines in the numbers of these animals – now species of conservation concern. [ABSTRACT FROM AUTHOR]

The feeding periodicity of three species of fishes in floodplain lagoons of the Macintyre River varied during 24 h cycles, however, peak feeding activity (around midday and late afternoon) was similar among the species studied, despite differences in their trophic position. In contrast, sampling season and site seemed to have a stronger effect on the composition of the diet than time of day. These findings have implications for studies of trophic dynamics and food web structure in floodplain lagoons. [ABSTRACT FROM AUTHOR]

Abstract: Direct ageing of fish can be a laborious and expensive task when age estimates from a large population are required, and often involves a degree of subjectivity. This study examined the application of general and generalized linear models that predict the age of fish from a range of efficiently and objectively measured covariates. The data sampled were from yellowfin bream (Acanthopagrus australis (Sparidae) (Owen, 1853)) and sand whiting (Sillago ciliata (Sillaginidae) Cuvier, 1829) populations from New South Wales, Australia. The covariates evaluated in the models were fish length, otolith weight, sex and location (the estuary from which the fish were sampled). Akaike Information Criteria were used for model selection and residual plots of the final models revealed a satisfactory fit to the observations. The best fitting model for each species included all covariates. An additional investigation considered whether general and generalized linear models that predict age from two different categories of biometric information outperform age-length keys with respect to subsequent estimates of total mortality from catch-curve analysis. The two categories of biometric information differed in the ease and cost with which the information could be collected. The first category only included fish length and location as covariates, whilst the second category also included otolith weight and sex. It was found that traditional age-length keys outperformed the predictive models that estimated age from only fish length and location, because the results from the models were prone to significant bias. However, when otolith weight and sex were added as covariates to the predictive models, some of them, including a generalized linear model with a Poisson-distributed response variable, performed similarly to the age-length key. Given that otolith weight and the sex of fish are cheaper to quantify than age from a sectioned otolith in many situations, general or generalized linear models may represent a cheaper and faster method of estimating mortality compared to age-length keys. Such models can also easily incorporate the influence of spatial, temporal and demographic variation. [Copyright &y& Elsevier]

The historical focus on offspring size has been to explain variation among populations, but there have been few attempts to determine whether variation is greatest at population scale. Offspring size variation is typically viewed as an adaptive response to changes in the relationship between offspring size and performance, yet direct tests remain elusive. We partitioned natural variation in offspring size for a marine invertebrate, Watersipora subtorquata, at a range of spatial and temporal scales across southeastern Australia, and we estimated the relationship between offspring size and performance at each population and time. There was significant variation in offspring size among populations, but regional differences explained only ~25% of the observed variation, suggesting that there should be a greater focus on small-scale variation in offspring size. We used our data to parameterize an optimality model to generate predictions of offspring size among different populations and times. Differences in the relationship between offspring size and postmetamorphic performance (and therefore changes in size of offspring that were predicted to maximize maternal fitness) among populations and times were associated with differences in offspring sizes among those populations and times. We suggest that interpopulation variation in offspring size can be an adaptive response to local conditions, but the optimal offspring size is surprisingly dynamic. [ABSTRACT FROM AUTHOR]

Abstract: The identification of marine habitats based on physical parameters is increasingly important for marine reserve design, allowing characterisation of habitat types over much wider areas than is possible from often patchy biological data. Marine management zones often contain a wide array of physical environments, which may not be captured in the biological sampling effort. The mismatch between biological and physical information leads to uncertainty in the application of bio-physical relationships at the broader management scale. In this study, a case study from northern Australia is used to demonstrate a methodology for defining uncertainties which result from the extrapolation of bio-physical associations across areas where detailed biological data is absent. In addition, uncertainties relating to the interpolation of physical data sets and that resulting from the cluster analysis applied to the physical data are calculated and mapped, providing marine managers with greater robustness in their analysis of habitat distributions. [Copyright &y& Elsevier]

Secondary metabolites from marine invertebrates, such as sponges, have diverse ecological roles and may be used in anti-predation, anti-fouling and spatial competition. The thin encrusting sponge Iotrochota sp., found on the Great Barrier Reef, Australia, contains several novel indoles that may aid in spatial competition. To examine whether levels of surrounding competition affect the toxicity of Iotrochota sp., 24 sponges from Salamander Reef, Central Great Barrier Reef, subject to either high or low levels of surrounding competition, were sampled. Tissue samples were taken from areas where the sponge was in direct competition with neighbouring sessile invertebrates, as well as from areas where competition was less obvious. Compounds from the tissue samples were extracted and tested in both cytotoxicity and anti-microbial assays. However, neither cytotoxicity nor anti-microbial activity varied significantly between the high and low competition treatments. Cytotoxicity was greatest among large sponges, suggesting that size is an important factor contributing to the toxicity of Iotrochota sp. sponges in this study. [ABSTRACT FROM AUTHOR]

Abstract: Mitochondrial DNA sequences were used to investigate phylogenetic and biogeographic relationships among Australian freshwater shrimp from the genus Caridina H. Milne Edwards, 1837 (Atyidae) and congeners from potential source populations throughout the Indo-West Pacific region. Numerous Australian taxa have close evolutionary relationships with non-Australian taxa from locations throughout the region, indicating a diverse origin of the Australian freshwater fauna. This implies many colonisations to or from Australia over a long period, and thus highlights the surprising adeptness of freshwater shrimp in dispersal across ocean barriers and the unity of much of the region’s freshwater biota. Interestingly, a study on Australia’s other main genus of atyid shrimp, Paratya Miers, 1882, inferred only a single colonisation. A number of potential species radiations within Australia were also identified. This agrees with patterns detected for a large number of Australian freshwater taxa, and so implies a vicariant explanation due to the development of colder, dryer climates during the late Miocene/early Pliocene. [Copyright &y& Elsevier]

1. Precise estimates of demographic rates are key components of population models used to predict the effects of stochastic environmental processes, harvest scenarios and extinction probability. 2. We used a 12-year photographic identification library of whale sharks from Ningaloo Reef, Western Australia to construct Cormack–Jolly–Seber (CJS) model estimates of survival within a capture–mark–recapture (CMR) framework. Estimated survival rates, population structure and assumptions regarding age at maturity, longevity and reproduction frequency were combined in a series of age-classified Leslie matrices to infer the potential trajectory of the population. 3. Using data from 111 individuals, there was evidence for time variation in apparent survival (φ) and recapture probability ( p). The null model gave a @ of 0·825 (95% CI: 0·727–0·893) and &pcirc; = 0·184 (95% CI: 0·121–0·271). The model-averaged annual @ ranged from 0·737 to 0·890. There was little evidence for a sex effect on survival. 4. Using standardized total length as a covariate in the CMR models indicated a size bias in φ. Ignoring the effects of time, a 5-m shark has a @ = 0·59 and a 9 m shark has @ = 0·81. 5. Of the 16 model combinations considered, 10 (63%) indicated a decreasing population (λ < 1). For models based on age at first reproduction (α) of 13 years, the mean age of reproducing females at the stable age distribution (Ā) ranged from 15 to 23 years, which increased to 29–37 years when α was assumed to be 25. 6. All model scenarios had higher total elasticities for non-reproductive female survival [ E( s nr)] compared to those for reproductive female survival [ E( s r)]. 7. Assuming relatively slow, but biologically realistic, vital rates (α = 25 and biennial reproduction) and size-biased survival probabilities, our results suggest that the Ningaloo Reef population of whale sharks is declining, although more reproductive data are clearly needed to confirm this conclusion. Combining relatively precise survival estimates from CMR studies with realistic assumptions of other vital rates provides a useful heuristic framework for determining the vulnerability of large oceanic predators for which few direct data exist. [ABSTRACT FROM AUTHOR]

1. Hypoxic conditions occur frequently during hot, dry summers in the small lentic waterbodies (billabongs) that occur on the floodplains of the Murray-Darling River system of Australia. Behavioural responses to progressive hypoxia were examined for the native and introduced floodplain fish of the Ovens River, an unregulated tributary of the Murray River in south-east Australia. 2. Given the high frequency of hypoxic episodes in billabongs on the Ovens River floodplain, it was hypothesised that all species would exhibit behaviours that would confer a degree of hypoxia-tolerance. Specifically, it was hypothesised that as hypoxia progressed, gill ventilation rates (GVRs) would increase and aquatic surface respiration (ASR) would become increasingly frequent. Fish were subjected to rapid, progressive hypoxia from normoxia to anoxia in open tanks. 3. All tested species exhibited behaviours consistent with their use of potentially hypoxic habitats. As hypoxia progressed, GVRs increased and all species, with the exception of oriental weatherloach, began to switch increasingly to ASR with 90% of individuals using ASR at various oxygen concentrations below 1.0 mg O2 L−1. Australian smelt, redfin perch and flat-headed galaxias were the first three species to rise to ASR, with 10% of individuals using ASR by 2.55, 2.29 and 2.21 mg O2 L−1 respectively. Goldfish and common carp were the last two species to rise to ASR, with 10% of individuals using ASR by 0.84 and 0.75 mg O2 L−1 respectively. In contrast to other species, oriental weatherloach largely ceased gill ventilation and used air-gulping as their primary means of respiration during severe hypoxia and anoxia. 4. Australian smelt, redfin perch and flat-headed galaxias were unable to maintain ASR under severe hypoxia, and began exhibiting erratic movements, termed terminal avoidance behaviour, and loss of equilibrium. All other species continued to use ASR through severe hypoxia and into anoxia. Following a rise to ASR, GVRs either remained steady or decreased slightly indicating partial or significant relief from hypoxic stress for these hypoxia-tolerant species. 5. Behavioural responses to progressive hypoxia amongst the fish species of the Ovens River floodplain indicate a generally high level of tolerance to periodic hypoxia. However, species-specific variation in hypoxia-tolerance may have implications for community structure of billabong fish communities following hypoxic events. [ABSTRACT FROM AUTHOR]

Gnathiid isopods are one of the most abundant groups of ectoparasites on coral reef fishes. They, and other isopods, have been shown to significantly affect the health and behaviour of many reef fish. Whether isopod emergence differs among habitats on coral reefs is not known. In this study, we measured emergence rates of parasitic isopods (Gnathiidea and Flabellifera) in six habitats at two sites at Lizard Island during new moon periods in March and December 2004. Isopods were collected from the periphery and centres of micro-reefs, patch reefs, continuous reefs, and from inter-reefal habitats (sand or rubble) with 1 m2 emergence traps. Sites (Casuarina and Coconut Beach) were located on opposite sides of Lizard Island. Live gnathiids were collected with light traps in November 2005 to investigate species differences between sites. At both sites, the most abundant gnathiid species was exclusive to that site. More gnathiid larvae emerged at night, and emergence of fed gnathiids (pranizae) and flabelliferan isopods was almost exclusively nocturnal. Diurnal emergence was greater at Coconut Beach than Casuarina Beach. Although emergence counts were not consistently affected by parameters such as habitat, site, or sampling period, gnathiid size and feeding state were. Where significant differences existed, gnathiids were larger and more often fed over reef borders than centrally. We suggest first stage larvae (Z1) have the largest influence on total abundance and are patchily distributed in accordance with adults from which they have recently hatched. As later stage larvae depend on fish, more successful (fed) and older larvae are found on the edges of reefs where appropriate hosts may be more abundant, or predation is lower. Gnathiids were over-dispersed in all habitats investigated, including apparently homogeneous beds of coral rubble and sand. This indicates that their distributions may be better predicted by very fine scale differences in substrate or that aggregations are the result of gregariousness and may be difficult to predict on the basis of substrate. Emergence traps collected comparatively few parasitic flabelliferan isopods. This community differed greatly from the previously described community of scavenging isopods at Lizard Island. These differences are probably the result of differences in trapping methodology. [ABSTRACT FROM AUTHOR]

In 1984 when Bill Williams highlighted the regionalization of salt lakes in Australia, little was known about lakes in the remote inland. It was thought the invertebrate fauna of such lakes was depauperate due to their being poor evolutionary loci associated with extreme episodicity. However, work in the last two decades, has shown the fauna of many inland lakes is relatively rich. Part of the reason for restricted faunas in the larger lakes is habitat homeogeneity. Nevertheless there is little diversification at the species level, indicating restrictions on speciation. There are also limits on diversity imposed by the harsh environment, as indicated by the lack of forms unable to survive severe desiccation, e.g. higher crustaceans. Lakes in central and the eastern inland are dominated by characteristic lower crustaceans such as Parartemia minuta, Daphniopsis queenslandensis, Moina baylyi, Trigonocypris globulosa and a new mytilocyprid ostracod, as well as some forms widespread in Australia and in salt lakes on other continents. This invertebrate fauna is just as distinct as those of other salt lake districts in southern Australia, further reinforcing the concept of regionalization in Australia. The fish fauna of central and eastern salt lakes is also largely specific, but the waterbirds are not as they have responded to the episodicity by nomadism and habitat flexibility. [ABSTRACT FROM AUTHOR]

The method of using sectioned otoliths to estimate age in three species of garfishes (family Hemiramphidae) was validated by: (1) staining fishes with the vital stain alizarin complexone (ALC) and periodically examining their otolith growth, and (2) marginal increment analyses. Staining fishes with ALC indicated that opaque zones were formed during winter and spring, but did not become visible on the otolith edge until late spring and summer. Hyporhamphus australis were found to be similar to the hemiramphids of the Atlantic in having fast growth rates and a maximum observed age of 4+ years old. Hyporhamphus regularis ardelio and Arrhamphus sclerolepis krefftii were found to be more similar to the southern sea garfish, Hyporhamphus melanochir, in being moderately long-lived, with maximum observed ages of 7+ years old for both species. Females grew faster and attained greater fork lengths than males for each species. Sectioned otoliths showed large variation in the appearance of opaque zones between the three species studied, with those from the wide-ranging, oceanic H. australis appearing inconsistent and diffuse when compared to the estuarine H. r. ardelio and A. s. krefftii. This variation was also apparent from fishes kept in aquaria, suggesting that the appearance of opaque zones in otoliths of these species is largely influenced by physiology, rather than by environmental conditions. [ABSTRACT FROM AUTHOR]

Densities of silver perch Bidyanus bidyanus eggs drifting in the Murray River, Australia, suggested a peak spawning time between 2100 and 0100 hours, and a propensity to drift in higher densities near shore and at the bottom of the water column. The results highlight the need to consider such spatial and temporal patterns when estimating species-specific drift abundances. [ABSTRACT FROM AUTHOR]

Aquatic invasive species cause deleterious environmental and economic impacts, and are rapidly spreading through ecosystems worldwide. Despite this, very few data sets exist that describe both the presence and the absence of invaders over long time periods. We have used Geographical Information Systems (GIS) to analyse time-series data describing the spread of the freshwater invasive New Zealand mudsnail, Potamopyrgus antipodarum, in Victoria, Australia, over 110 years. We have mapped the snail's spread, estimated the percentage of stream length invaded through time, calculated the functional form of the spread rate, and investigated the role that the two proposed vectors — fish stocking and angling — have had in this invasion. Since it was first found in 1895, P. antipodarum has expanded its range in Victoria and now occurs throughout much of the southern and central areas of the state. The north of the state is relatively less invaded than the south, with the division corresponding approximately to the presence of the Great Dividing Range. We show that the snail's range has been increasing at an approximately exponential rate and estimate that 20% of total Victorian stream length is currently invaded. We also show that using long-term data can change the outcome of analyses of the relationship between vectors of spread and invasion status of separate catchments. When our time-series data were aggregated through time, the total numbers of fish stocking events and angling activity were both correlated with invasion. However, when the time-series data were used and the number of fish stocking events calculated up until the date of invasion, no relationships with stocking were found. These results underline the role that time-series data, based on both presences and absences, have to play when investigating the spread of invasive species. [ABSTRACT FROM AUTHOR]

The article cites a study conducted in Southern Australia regarding the usefulness of surrogates of biodiversity in marine benthic communities in estimating complex variables describing community structure. In adopting a surrogate measure, it is assumed that the relationship between the surrogates and total richness or diversity is consistent in both space and time. The robustness of potential surrogates of familial richness and multivariate community structure for macrofauna communities inhabiting artificial kelp holdfasts was examined by comparing among communities of dissimilar ages and among communities established at different times of the year. The authors suggest that the choice of technique for selecting surrogate taxa depends greatly on the nature of the pilot data available.

Quantitative surveys revealed high diversity (species richness) of sponges (150 species) in the previously little explored Dampier Archipelago, northwestern Australia. Classification analyses disclosed 11 station groups with high internal heterogeneity in species composition, however some spatial patterns were evident. The composition of sponge assemblages varied with environmental factors such as substrate type (coral, igneous rock, limestone rock), aspect (exposed, protected), substrate configuration (limestone platform, dissected reef) and depth. Most of the species (61%) reported from the Dampier Archipelago were rare (found at one or two stations). The number of species found at only one location was high (48%), supporting previous findings that northwestern Australia has high sponge endemism. As a result of all sponge surveys undertaken in the archipelago (qualitative and quantitative, subtidal and intertidal), 275 sponge species have now been reported from the area. This number indicates high species diversity in the region. Estimations of diversity based on non-parametric modelling suggests that there are potentially more species (range 245-346) than presently recorded in the archipelago. [ABSTRACT FROM AUTHOR]

Spawning sites are a critical and often scarce resource for aquatic-breeding amphibians, including invasive species such as the cane toad ( Bufo marinus). If toads select spawning sites based on habitat characteristics, we can potentially manipulate those characteristics to either enhance or reduce their suitability as breeding sites. We surveyed 25 spawning sites used by cane toads, and 25 adjacent unused sites, in an area of tropical Australia recently invaded by these feral anurans. Water chemistry (pH, conductivity, salinity, turbidity) was virtually identical between the two sets of waterbodies, but habitat characteristics were very different. Toads selectively oviposited in shallow pools with gradual rather than steep slopes, and with open (unvegetated) gradually sloping muddy banks. They avoided flowing water, and pools with steep surrounds. In these respects, cane toads broadly resemble previously studied toad species in other parts of the world, as well as conspecifics within their natural range in South America. [ABSTRACT FROM AUTHOR]

The mortality of hooked-and-released sand whiting (Sillago ciliata) and the key contributing factors were determined during a recreational fishing event in northern New South Wales, Australia. Participating anglers caught 124 sand whiting, of which 60 were tagged with plastic t-bar anchor tags, and then released into replicate sea cages. In all, 109 sand whiting were seined (54 were tagged) and similarly released into replicate sea cages for use as controls. All fish were monitored for mortalities over 7 days. There were no measurable effects of confinement in the sea cages on the stress (measured as concentrations of plasma glucose) of hooked or seined fish. Ten hooked-and-released (four non-tagged, six tagged) and two control (both tagged) sand whiting died during the monitoring period and mostly within 48h of capture, providing adjusted mortality rates (i.e. accounting for mortalities of control fish) of approximately 6% for total, tagged, and non-tagged fish. Anatomical hook location (oesophagus-ingested hooks) and bait type (beach worms, Australonuphis teres) were significant predictors of mortality (p >0.05). The results support current recreational fishing gears and practices for the catch and release of sand whiting. [Copyright &y& Elsevier]

Spatial autocorrelation in ecological systems is a critical issue for monitoring (and a general understanding of ecological dynamics) yet there are very few data available, especially for riverine systems. Here, we report here on assemblage-level autocorrelation in the benthic-invertebrate assemblages of riffles in two adjacent, relatively pristine rivers in south-eastern Victoria, Australia (40-km reaches of the Wellington [surveys in summers of 1996 and 1997] and Wonnangatta Rivers [survey in summer of 1996 only], with 16 sites in each river). We found that analyses were similar if the data were resolved to family or to species level. Spatial autocorrelation was assessed by using Mantel-tests for the data partitioned into different sets of spatial separations of survey sites (e.g. 0–6 km, 6–12 km, etc.). We found strong small-scale (≤6 km) autocorrelation in the Wellington River, which is consistent with known dispersal abilities of many aquatic invertebrates. Surprisingly, there were strong negative correlations at longer distance classes for the Wellington River in one of the two summers (20–40 km) and the Wonnangatta River (12–20 km). That two largely unimpacted, adjacent rivers should have such different autocorrelation patterns suggests that impact assessment cannot assume dependence or independence of sites a priori. We discuss the implications of these results for use of “reference” sites to assess impacts at nominally affected sites. [ABSTRACT FROM AUTHOR]

Locomotion of the box jellyfish Chiropsalmus sp. (cf quadrigatus)1 (Haeckel) and Chironex fleckeri (Southcott) was analysed using digital video. Specimens of Chiropsalmus sp. and C. fleckeri were collected in 2001 and 2002, respectively, from coastal waters of Northern Queensland, Australia. Chiropsalmus sp. animals were videoed swimming in an aquarium, and C. fleckeri in a large outdoor tank. Locomotor sequences of nine Chiropsalmus sp. and seven C. fleckeri individuals were analysed using video techniques. A subset of animals had fluorescent dye injected into the sub-umbrellar cavity, to allow observation of water movements during ejection from the bell. Both species used an intermittent style of jet propulsion similar to that documented for some other species of cubozoan medusae. Computer analysis allowed examination of positions of bell parts over time intervals (0.04 s) by comparing coordinates of nodes marked on various bell parts using imaging software. Examination of node coordinates allowed a detailed qualitative description of gait, in addition to quantitative statistical analyses. General linear modelling showed that interspecific differences in locomotion were explicable in terms of body size. Larger animals of both species tended to swim faster, and with a lower pulse frequency, than smaller individuals. Smaller animals also tended to swim faster relative to their bell diameter. [ABSTRACT FROM AUTHOR]

Comparisons of the Irrawaddy dolphin, Orcaella brevirostris, between Australian and Asian sites documented geographic differences in height of dorsal fin, presence or absence of a median dorsal groove in front of the dorsal fin, and coloration (presence or absence of a dorsal cape). Analysis of genetic data provided support for two clades within the Asian samples, the Mekong River samples from Cambodia and southern Laos, and all other marine and freshwater sites from Thailand, Indonesia, and the Philippines. The major separation, however, was between sites in Asia and those from Australia (5.9% of base pair differences, compared with 1.2% for within Australia and 1.5% for within Asia). Within a 403 base segment of the mrDNA control region, Australian specimens had 17 diagnostic sites with 16 fixed base pair differences and one insertion/deletion. Consistent, statistically significant differences in skull characters of Australian specimens have previously been demonstrated and are reviewed in this paper. There was a high concordance in character differences demonstrated between O. brevirostris from all Asian sites and Australian specimens, especially in the genetic and osteological characters. Based on the range and concordance of character differences, we propose that the Australian dolphins be recognized as a new species, Orcaella heinsohni (suggested common name: Australian snubfin dolphin). [ABSTRACT FROM AUTHOR]

Abstract Human transport hubs, such as shipping ports, airports and mail centers are important foci for the spread of non-indigenous species. High relative abundance in a transport hub has been proposed as a correlate of invasion success, since abundant species are thought more likely to colonize vectors and to be transported more frequently. We here evaluate the relative importance of vector characteristics and local source assemblages in determining the pool of species that is transported by hull fouling on recreational boats. We compared the resident fouling communities of three recreational boat harbors in Australia with the assemblages on the hulls of boats that travel between them. We used data on the recent travel and maintenance history of the boats to evaluate correlates of transport probability and the potential for intra-coastal spread of fouling organisms. Invertebrate assemblages on heavily fouled vessels reflected the composition of biotic assemblages within the marina in which they were moored, but by itself, relative abundance in the source port was not a reliable predictor of transport probability. More important was the age of the antifouling paint on the vessels hulls, which acted selectively on some groups of organisms. Movements of vessels were characterized by fidelity (vessels remaining close to homeport) interspersed with promiscuity (vessels traveling to a diverse pool of destinations). In an infested harbor, measures taken to increase the resistance of vectors to colonization by the invader should be effective in slowing the rate of spread to other locations, by decreasing the overall frequency of transport. [ABSTRACT FROM AUTHOR]

The most common modification of saltmarsh habitat for mosquito control in Australia is runnelling, a system of shallow channels increasing seawater exchange in pools high on the marsh. Local effects within the immediate vicinity of runnels were examined by testing the hypothesis that fish assemblages immediately alongside runnels differ from those further away. Nekton assemblages were sampled using pop nets in winter (May) and summer (December) on a saltmarsh in southeast Queensland, alongside runnels and further (30 m) away, at two distances from a mangrove-lined intertidal creek. Nekton assemblages were dominated numerically (50–80%) by one or two species of small fish ( Ambassis marianus, Mugilogobius stigmaticus), and a commercially important prawn, Fenneropenaeus merguiensis. In winter, nekton assemblages alongside runnels were significantly different from those further away. Species richness, total nekton densities and densities of several individual species were higher away from runnels, but only at sites far from the creek. No differences in species richness or densities were found in summer. During both periods, nekton assemblages differed strongly with distance from the creek, with more species and higher densities of most species near the creek. For most species, the overall effect of runnelling appears to be a reduction in abundances in the immediate vicinity of runnels, at some times of year. This is probably related to lower prey availability near runnels. Given the extent of runnelling in some parts of Australia, even this local reduction in densities extending no more than 30 m from runnels means that nekton may be adversely affected over a large total area. The apparent influence of runnels on nekton densities highlights the potential effects of saltmarsh modification on non-target animals that should be considered as this management technique becomes more prevalent. [ABSTRACT FROM AUTHOR]

We investigated the behavioural responses of two gobiid fish species to temperature to determine if differences in behaviour and ventilation rate might explain any apparent vertical zonation. A survey of the shore at Manly, Moreton Bay revealed Favonigobius exquisitus to dominate the lower shore and Pseudogobius sp.4 the upper shore. These species were exposed to a range of temperatures (15–40°C) in aquaria for up to 6 h. At 20 °C F. exquisitus exhibited a mean gill ventilation rate of 26 ± 1.4 bpm (beats per minute) differing significantly from Pseudogobius, which ventilated at a fivefold greater rate of 143 ± 6 bpm. The ventilation rate in F. exquisitus underwent a fivefold increase from normal local water temperature (20 °C) to high temperature (35 °C) conditions, whereas that of Pseudogobius did not even double, suggesting that Pseudogobius sp. is a better thermal regulator than F. exquisitus.While both species emerged from the water at high temperatures (>30 °C) the behaviours they exhibited while immersed at high temperature were quite different. F. exquisitus undertook vertical displacement movements we interpret as an avoidance response, whereas Pseudogobius sp. appeared to use a coping strategy involving movements that might renew the water mass adjacent to its body. The thermal tolerances and behaviours of F. exquisitus and Pseudogobius sp. are in broad agreement with their vertical distribution on the shore. [ABSTRACT FROM AUTHOR]

Rivers of Western Queensland, Australia, represent a discontinuous and variable aquatic habitat for the freshwater fauna of the region. Rivers periodically fluctuate between being highly fragmented, with numerous disconnected waterholes and ephemeral channels, and being highly connected by a dominant system of anastomosing channels. We used mitochondrial sequences to investigate the genetic structure and inferred patterns of dispersal associated with this flow regime for the freshwater prawn, Macrobrachium australiense (Decapoda: Palaemonidae), sampling 28 localities throughout eight catchments. Based on a 505 base pair fragment of mitochondrial cytochrome c oxidase subunit I, we identified 98 haplotypes in a sample of 402 individuals. The haplotypes clustered into two main clades corresponding geographically to the major drainages: the Lake Eyre and Murray-Darling basins. Populations of M. australiense inhabiting the two basins appear to have diverged around 800000 years ago (estimated sequence divergence of 1.6%). Analysis of population differentiation indicated contemporary high levels of genetic subdivision and restricted gene flow among populations within and among catchments. Phylogenetic analysis detected a series of historical range expansions in the region and we suggest that climate fluctuations during the Pleistocene have resulted in extensive floods that have promoted historical movements of aquatic organisms across catchment boundaries. [ABSTRACT FROM AUTHOR]

This study has tested the following main hypotheses. (1) The composition of fish assemblages in nearshore waters along the lower west coast of Australia will differ significantly among four habitat types (1–4), which could be distinguished quantitatively from each other by differences in the values for a statistically selected suite of enduring environmental variables. (2) The extents of the differences in ichthyofaunal composition among the four habitat types will statistically match those in the suite of environmental variables that distinguish those habitat types. A 60.5 m long seine net, with 9 mm mesh in the bunt, was used seasonally for 2 years to sample fish from sites representing each of the four nearshore habitat types, which differed broadly in their exposure to wave activity and the extent and location of seagrass beds. The compositions of the fish faunas in each habitat type were significantly different from each other in all but one case. Ichthyofaunal composition did not differ significantly between years in any habitat type and differed significantly among seasons in only one habitat type. The arrangement of the rank orders of similarity in matrices constructed from the abundances of the fish species at each site also did not differ between years but did differ among seasons. Moreover, the arrangement of the ranks in the similarity matrices produced from the ichthyofaunal data recorded at the various sites in each season were significantly correlated with that in the distance matrix constructed from the environmental data for those sites, with the correlation (ρ) ranging from 0.476 in winter to 0.696 in autumn. These results thus demonstrate that the extents of the differences in the fish compositions among the various habitat types parallel those in the environmental data for the corresponding habitat types. The subset of species that provided the best correlation with the environmental distance matrix, and which was thus most responsible for distinguishing among the fish compositions at the four habitat types, was also determined for each season. [Copyright &y& Elsevier]